I recently touched up the prosound my old GBC that I've used for experiments. I'm tapping the signals off the same point (basically right off the CPU pins). But I've done away with the caps and just placed resistors in series, about 100 ohm or so. This DC couples the signal completely for the flattest possible frequency response. This relies on the receiving equipment having DC blocking caps, which is almost always the case.

Whether or not you put the cap in series, I recommend putting a resistor in series as well as a protection against a short circuit to ground or an output to output connection. With just the cap in series, there is a dead short to the other side for frequencies above DC (0 Hz) which may damage the CPU if an incorrect connection is made.

You can use a polarized capacitor for the signal coupling if you put the + side toward the CPU. The CPU will always produce frequencies between 0 and +5V, so the polarity requirement should not be violated.

I'll have to try the extra cap on the voltage rail to see if it gets rid of the horrible buzz.

Paging ThursdayCustoms.

You think it's possible to make a small-form factor pcb with said components as a gbc bass mod pcb?

Why would you need a PCB for this? It actually seems far easier to have the components hanging in free air for this one.

I was thinking a small, in-line, thin, rectangular pcb with smd components. One pcb for each channel so that they can be made in bulk. If I can get ito it soon, I'll see about doing a quick drawing and post it up.

What I imagine is a pcb similar in size to the low-battery led pcbs that kitsch sells.

*edit*

There reason why I am thinking about pcbs versus the free hanging bits is for this mod to be available to people who don't have the best soldering skills in the world. The way I did it is fairly involved and takes a bit of time and patience. A PCB would save time and the end user would only have to solder 4 wires at most.

I would, myself, directly replace the smd components on the pcb of the gbc but I don't have the proper tools to work with smd components.

I have actually thought of doing this. The main problem is that I have not been able to find a 470uf capacitor as small as I would like. Could only find size D or E. Kitsch has this now though: http://store.kitsch-bent.com/product/gbamp

I have actually thought of doing this. The main problem is that I have not been able to find a 470uf capacitor as small as I would like. Could only find size D or E. Kitsch has this now though: http://store.kitsch-bent.com/product/gbamp

I have actually thought of doing this. The main problem is that I have not been able to find a 470uf capacitor as small as I would like. Could only find size D or E. Kitsch has this now though: http://store.kitsch-bent.com/product/gbamp

The 470uf cap would be something separate though. I was referring to the bass mod part...

I have actually thought of doing this. The main problem is that I have not been able to find a 470uf capacitor as small as I would like. Could only find size D or E. Kitsch has this now though: http://store.kitsch-bent.com/product/gbamp